EP0034128B1

EP0034128B1 - Pin and relevant seat to connect together two elements

Info

Publication number: EP0034128B1
Application number: EP81830014A
Authority: EP
Inventors: Pierluigi Ranzanigo
Original assignee: SETI SpA
Current assignee: SETI SpA
Priority date: 1980-02-06
Filing date: 1981-01-27
Publication date: 1985-07-10
Also published as: AR222734A1; AR223255A1; IT8019719A0; ES254360Y; BR8008448A; MX151718A; EP0034128A1; ATE14238T1; ES254360U; DE3171285D1; IT1141164B

Description

The present invention refers to a pin and the relevant seat to connect together two facing elements, such as for example a box and its cover, a frame supporting electrical equipment at the opening of an enclosing box, and this by accomplishing the locking with a rotation of 90°.
Attempts to obtain pins accomplishing the locking by a rotation of 90° have already been made, using screws whose threading was interrupted by two plane millings parallel to each other and to the screw axis, so that the screw interrupted coils would have gripped, with a self-threading action, the internal part of a suitable section. These screws, however, have not given satisfactory results mainly because their gripping action was limited and their axial holding was completely unreliable.
On the other hand the possibility of very rapidly connecting together two elements by the rotation of 90° of a suitable pin is very important in order to eliminate screws and relevant threaded bushes, which imply a high production cost and a considerable waste of time in screwing and unscrewing such elements.
The US-A-3272061, according to the precharacterising part of claim 1, describes a pin and relevant seat, apt to connect together two elements, by rotating by an angle of 90° the pin in the seat, using a screwdriver. Rotations greater than 90° are prevented by ribs provided in the seat.
According to this US Patent, the seat is formed into an accessory element to be interposed between the elements to be connected together.
The present invention proposes a new type of pin and relevant seat able to insure a perfect connection by a 90° rotation in one direction and the perfect release by a 90° rotation in the opposite direction, the seat being formed directly in one of the element to be connected.
The pin and relevant seat of the invention are characterised by the features in the characterising part of claim 1.
An example of this invention, however, not limitative of the possible realizations, is shown in the enclosed tables in which:

Figures 1 and 2 show, in an enlarged scale, the complete pin with the tabs seen from the front and in profile respectively;
Figure 3 is a section ideally obtained by cutting the pin along line A-A of Figure 2;
Figure 4 shows a horizontal section of the seat in which the pin of the previous figures can be driven;
Figure 5 shows a section ideally obtained by cutting the seat along line B-B of Figure 4.

As shown in Figure 1, 2 and 3, the pin of this invention is made of a cylindrical stem 1, provided with a head 2 and a slot 3, similar to the milled head of a screw, the slot being suitable to allow the operation with a.strongly-built screwdriver.
Two couples of tabs are fixed on stem 1, preferably on the half part closer to the head; the first couple (upper tabs 4 and 5) diametrically opposed and the second couple (lower tabs 6 and 7) also diametrically opposed. All tabs are arranged so as to lie on the same plane passing through the stem axis. Each tab is delimited by an inclined side, which determines its lateral extent, and by a side perpendicular to the stem axis. The upper tabs 4 and 5 present their inclined sides diverging downwardly, while the lower tabs 6 and 7 present their inclined sides diverging upwardly, as clearly indicated in Figures 2 and 5.
Tabs 4, 5, 6 and 7 are usually obtained by upsetting the stem material, so that, on the sides of each tab, cavities 4', 5', 6' and 7' respectively are created (see Fig. 5), resulting from the removal of the material necessary to form the relative tabs. Theoretically, the inclined side and the side perpendicular to the axis, which delimit each tab, should converge in a sharp vertex, but in practice the upsetting of the material forms a round blunting that is preferable to a sharp vertex because it facilitates the correct tab penetration in the seat material as will be explained later.
The pin presents, emerging from the lower part of head 2, a crown 8 (see also Fig. 5) having a sharp edge pointing downward, the purpose of which will also be explained later.
Figures 4 and 5, besides showing the pin of the invention in a transversal section and in a longitudinal section respectively, present also the seat in which such pin will be housed. This seat is made of a cylindrical cavity 9, having a diameter slightly larger than that of the stem 1, and provided, on two sides diametrically opposed, of longitudinal grooves 10 and 11; these grooves are extended up to the opening of the cavity 9 so as to allow the introduction of the pin and tabs 4 to 7. Of course the grooves 10 and 11 are also wider and deeper than the respective tabs.
As shown in Figure 4, the cavity 9 is further delimited by two opposite thin walls 12 and 13 shaped in such a way as to form a little more than a quarter of an arc of the total cylindrical wall plus the wall of the corresponding groove 10 or 11. Their ends are delimited, on one side by the solid parts 14 and 15 respectively, thus internally completing the cylindrical wall of the cavity 9, and on the other side by the respective groove 10 or 11. In this way, the thin walls 12 and 13 constitute two elastically yielding parts.
The seat thus created is generally obtained on a wall 16 which forms the lateral side of a groove of insulating material, for example plastics, and arranged so as to protrude from this side toward the inside of the box itself. Upward the seat has its opening on a plane 17 or at the level of plane 17, on which the plane 18 of another element is positioned; the plane 18 can be the edge of the cover used to seal the box, or the top of a basket- type support entering inside the box to fix electrical parts or the frame supporting interchangeable electrical equipments, etc. Plane 18 presents a hole 19 having a diameter about the same as that of the cavity 9, which is aligned coaxially with the cavity thus allowing the introduction of stem 1.
To lock the pin once the planes 18 and 19 are overlapping and aligned, the operations are the following: the pin, angularly oriented so that the tabs 4 and 5 slide inside the grooves 10 and 11, is inserted in cavity 9 until the crown 8 rests on the plane 18, as shown in Figures 4 and 5. At this point a screwdriver is inserted in the slot 3, the head 2 of the pin is pressed down and at the same time a rotation to the right of about 90° is exerted.
During this operation, the tabs 4 to 7 will press on the walls 12 and 13, which will elastically yield, digging a track on the wall itself and gripping on the material, until reaching the final position indicated in Figure 4 with dashed lines and in Figure 5 with solid lines. Evidently, in such position the pin is locked both by the track which it has digged and by the pressure exerted by the elastic walls 12 and 13.
It is also evident that, should the operator inadvertently try to exceed the rotation of 90°, the solid parts 14 and 15 will oppose resistance to prevent this further operation.
In this locked position, the sharp-edged crown 8 will penetrate in the material of the plane 18, acting on the latter not only with the pressure that keeps it against the plane 17, but also with a horizontal constraint. In this way, any sliding parallel to the plane 17, in the direction indicated by the arrows, is prevented, thus eliminating possible relative movements, for example between the box and its cover; this could not be avoided beforehand by the use of simple screws.
As stated earlier, the tabs 4 and 5 present the inclined sides diverging downwardly, while the tabs 6 and 7 present their inclined sides diverging upwardly. This arrangement makes easier the introduction and the removal of the pin, because the inclined sides of the tabs 6 and 7 represent an inducement to the introduction, while the inclined sides of the tabs 4 and 5 represent an inducement to the removal, thus preventing interferences with the edges of the holes crossed by the pin.
Of course, the invention is not limited to the above illustrated realization.

Claims

1. Pin and appropriate seat apt to connect together two elements by rotating by an angle of about 90° the pin in the seat, wherein the pin has an enlarged head (2) provided with a slot (3) for cooperation with a screwdriver, and a stem (1) provided with gripping tabs (4, 5, 6, 7) protruding from the stem in diametrically opposed directions, and wherein the seat has a cylindrical cavity (9) designed to be elastically deformable by the tabs and to limit the rotation of the pin in the seat, characterised in that the pin is provided with two couples of gripping tabs (4, 5) and (6, 7) arranged at different levels along the stem itself, each tab being delimited by one side inclined with respect to the stem axis and by another side perpendicular to this axis, the couple of tabs (4, 5) closer to the head (2) of the pin presenting the inclined sides diverging downwardly away from the head, while the couple of tabs (6, 7) closer to the end of the pin opposite to said head (2) presenting the inclined sides diverging upwardly towards the head, and in that the cylindrical cavity (9) of the seat is provided with two diametrically opposed longitudinal grooves (10, 11) and further delimited by two opposite walls (12, 13) extending between the grooves along an arc of about 90° and designed to be elastically deformable by said gripping tabs to make the locking of the tabs in the seat material easier due to elastic yielding of these walls, said walls ending in solid parts (14, 15) having a greater thickness with respect to the walls (12, 13), to prevent further advancement of the tabs.

2. Pin and seat as in claim 1, characterised in that the seat is formed directly in one of the two elements to be connected together.

3. Pin and seat as in claims 1 and 2, characterised in that the pin presents a sharp-edged crown (8) directed parallel to its axis, and protruding from the lower part of its head (2), said sharp-edged crown being apt to rest and to grip on a flat face of the upper one of the two elements to be connected which is not provided with said seat.